Currently, diagnosis of arthritic disorders requires physical examination of the patient by a skilled medical practitioner, immunological examination of synovial fluid and/or blood, X-ray investigation, magnetic resonance imaging (MRI) or any combination of the these procedures. Such procedures:
i) require the services of a rheumatology specialist, immunologists and skilled technical staff, PA1 ii) are time consuming and costly, PA1 iii) are not always reliable PA1 iv) can only detect arthritic disorders after severe damage to the affected joint has already appeared.
There is therefore the need for a rapid, non-subjective, low cost and non-labour intensive method for the diagnosis of arthritic disorders which does not require highly skilled personnel.
It has been proposed in U.S. Pat. No. 5,038,039 dated Aug. 6th 1991, "Method of Detecting the Presence of Anomalies in Biological Tissues and Cells in Natural and Cultured Form by Infrared Spectroscopy", P. T. T. Wong and B. Rigas, that infrared spectroscopy can be used to detect anomalies in biological tissues and cells. Such a method is not easily applicable to the diagnosis of arthritic disorders, as tissue from the affected joints is not usually available. This method does not include infrared spectroscopic analysis of biological fluids, due to the inherent problems associated with such an analysis caused by the presence of extremely strong interfering infrared absorptions from the water present in biological fluids.
It has been reported that the intensity of a novel infrared absorption band observed in synovial fluid films may be useful as an indicator of arthritis (Eysel et al., Applied Spectroscopy Vol. 47, No. 9, p. 1519-1521, 1993). However, this feature, attributed to metabolically produced CO.sub.2 trapped within the matrix of the film, may be considered to be a marker of inflammatory conditions, which are accompanied by increased metabolic activity and so elevated levels of CO.sub.2. Thus such a technique would provide a metabolic profile of the joint (which may, for example be affected by infection) rather than a clinically relevant diagnosis of arthritis. The invention reported here on the other hand concentrates on differences in the physical and chemical properties of synovial fluid which directly result from or cause degeneration of the joint and which are represented as changes in the infrared spectrum of the fluid or film.
Russian Patent No. 1,686,357 issued Oct. 23, 1991 discloses a method for diagnosing rheumatoid arthritis activity level by isolating erythrocyte suspension from blood, recording an EPR spectrum and determining the arthritic activity.
U.S. Pat. No. 4,499,186 issued Feb. 12, 1985 to Teodorescu et al. describes a spectrophotometric diagnosis of rheumatoid arthritis by blocking calcium ions in a blood sample.